1. Technical Field
Embodiments of the invention relate to liquid phase deposition of a high-k dielectric material on a semiconductor substrate.
2. Description of Related Art
Dielectric materials with high dielectric constant (high-k) are desirable for use as gate dielectrics in semiconductor devices.
Conventional methods of depositing a high-k dielectric film on a semiconductor substrate include physical vapor deposition (PVD), chemical vapor deposition (CVD) and atomic layer deposition (ALD). ALD is a gas-phase thin film deposition method based on alternate saturative surface reactions.
In ALD, separate pulses of reactive vapor streams are led to a process chamber containing a semiconductor substrate, where the pulses can be separated by purging or evacuating. During each pulse, a self-limited chemisorbed layer is formed on the surface of the semiconductor substrate. The reaction chamber is then purged or evacuated to remove traces of non-chemisorbed first reactant from the gas phase. In the next pulse, the chemisorbed layer is exposed to a second reactant which forms a thin film of dielectric material on the semiconductor substrate. This cycle may be repeated until a desired thickness is obtained for the dielectric material deposited onto the substrate. Although the ALD method may have advantages over the PVD and CVD methods, the ALD method still suffers from problems with film quality, film continuity and film contamination.